It is well-known in the prior art to provide a plurality of electrical terminals which are stamped and formed in a stamping press from a continuous strip of metal, with a portion of the metal strip remaining integral with each of the terminals to provide a carrier strip along which the terminals are serially spaced. The integral carrier strip allows for conveyance of the terminals in serial relationship through an insertion machine, typically having a severing station where terminals are removed from the strip, and an insertion station where the removed terminals are individually inserted within a workpiece, such as a printed circuit board, a connector housing, or other workpiece to which the terminals are either mounted or contained. In practice the terminals are inserted one at a time by the insertion machine, necessitating indexing of the carrier strip repeatedly to position each terminal in succession at the severing and insertion stations. The speed of the required indexing and consequently the speed of the insertion machine operation depends on the amount of spacing between adjacent terminals along the integral carrier strip. In turn, spacing of the terminals depends upon the size and the complexity of the terminals stamped and formed from the continual strip of metal. More particularly, the larger or more complex the three dimensional bodies of the terminals, the greater the amount of metal must be consumed from the metal strip to form the terminals. The greater the amount of metal consumed, the further apart the terminals are required to be spaced along the integral carrier strip. Often such spacing becomes excessive since substantial lost motion and assembly time results when the terminals must be individually indexed by advancing repeatedly the carrier strip to the severing and insertion stations of the machine.
It is desirable to reduce to time lost in individually indexing the terminals by severing and inserting a plurality of terminals simultaneously. However, the spacing of a plurality of terminals along the carrier strip does not often coincide with the required spacing of the terminals when mounted or contained within a workpiece. Thus it has been heretofore difficult to transfer a plurality of terminals simultaneously from a carrier strip to a workpiece without eliminating the need for indexing the terminals or the workpiece to achieve the required spacing of the terminals on the workpiece.
According to the present invention, a plurality of carrier strips are adapted to be stacked together immediately prior to being simultaneously conveyed to an insertion machine. The stacked carrier strips are mutually offset such that the terminals thereof are serially arranged on closer spacing than are the terminals along any one of the stacked carrier strips. Whereas closely spacing the terminals for simultaneous insertion into a workpiece is achieved, maintaining the carrier strips in stacked registration is difficult. It was first believed that the carrier strips should be assembled in stacked relationship and than fastened together to make a single composite carrier strip which could be reeled up on a spool for storage and subsequently supplied to the insertion machine when needed. Such a procedure has a disadvantage in that the composite strip has to be fabricated as a subassembly from individual carrier strips which were themselves already reeled up and stored on spools as the carrier strips emerged from stamping and forming presses. More particularly individual carrier strips are required to be unreeled, registered in stacked relationship, fastened together to make a composite strip and then the composite strip reeled up on a separate spool. The present invention advantageously eliminates fabrication of the subassembly. The present invention eliminates the need for individual carrier strips to be unreeled from their original storage spools until finally utilized in an insertion machine. Desired registration of the individual strips in stacked relationship is attained without further processing or modification of the individual carrier strips. Since the individual carrier strips are undisturbed from their original storage spools, the carrier strips can be used either individually or in stacked relationship as desired without a need for modifying the carrier strip or terminals and without a need for fabricating a subassembly. As a further advantage each individual carrier strip is designed such that any selected length or part of the individual carrier strip is stackable upon itself or upon another additional part of the same carrier strip. This is accomplished by stamping and forming an interlocking geometry of the carrier strip during the same stamping and forming operation utilized to form the carrier strip and the integral terminals thereof.
Each of the stacked carrier strips is stamped and formed with an interlocking geometry which interlocks the carrier strips together. The interlocking geometry thus assures proper registration between stacked layers of strips and thereby precisely locates the terminals of the stacked carrier strips serially in compact spacing. This permits a properly designed insertion machine to simultaneously insert a plurality of terminals within equally precisely arranged locations in a workpiece. The interlocking geometry is purposely selected to permit an individual carrier strip to be stacked upon itself thereby advantageously eliminating the need for matching varied geometries of carrier strips required for interlocking. Advantageously only a single geometry of carrier strip is required to interlock a plurality of carrier strips in stacked configurations.